The present invention relates to an electric switch assembly and, more particularly, to an electric switch assembly of a type comprising at least one movable contact element and a plurality of fixed contacts. The movable contact element can electrically connect at least one of the fixed contacts to any one of the remaining fixed contacts.
The electric switch assembly to which the present invention pertains is, most suited for use as a channel selector in audio and/or visual signal handling instruments such as video information recording and/or reproducing devices, radio receivers, television sets, record players and so on but need not be exclusively used for those purposes.
A type of electric switch assembly referred to above is in fact known in the prior art commercially is available. The known electric switch assembly of the type referred to above comprises a substrate of electrically insulating material having a plurality of fixed contacts, which are rigidly mounted on at least one surface of said substrate, and a movable contact element rigidly mounted on a disc of electrically insulating material. The disc is mounted on a manually rotatable shaft for rotation together therewith so that, during rotation of the disc, the movable contact element moves in a substantially circular path. Therefore, the fixed contacts are arranged in a circular configuration on alignment with the circular path of movement of the movable contact element while the movable contact element is so sized as to bridge between two or more of the fixed contacts.
In this prior art electric switch assembly, the fixed contacts are electrically connected to respective terminal members, rigidly secured to an outer peripheral edge of the substrate, by means of printed circuits imprinted on one surface of said substrate. Rigid mounting of the fixed contacts on the surface of the substrate is carried out by the use of metallic eyelets or similar fastening members, equal in number to the number of the fixed contacts. These eyelets or similar fastening members are staked to electrically and physically connect the fixed contacts to the printed circuits on the substrate. The movable contact element is also rigidly mounted on the rotary disc in a substantially similar manner to the mounting of the fixed contacts on the substrate. Even the terminal members, which are separate from the fixed contacts, but electrically connected thereto through the printed circuits, are rigidly mounted on the substrate in a complicated manner comparable to the mounting of any of the fixed contacts and the movable contact element.
Moreover, portions of the fixed contacts which are selectively engaged with the movable contact element are each shaped such that electrical connection between the movable contact element and any one of the fixed contacts is achieved by inserting said movable contact element in between the surface of the substrate and that portion of the fixed contact during rotation of the disc carrying said movable contact element. Unless that portion of each of the fixed contacts is adequately shaped, insertion of the movable contact element between the substrate and that portion of any one of the fixed contacts during rotation of the disc will be hampered because the movable contact element tends to abut against a lateral side edge of that portion of the fixed contact which is elastically biased towards the substrate.
The prior art electric switch assembly of the construction described above requires a complicated manufacturing procedure. This is a result of the complicated shape required for that portion of any one of the fixed contacts and partly because of the employment of the eyelets or similar fastening members necessary to secure the fixed contacts to the substrate and also secure the movable contact element to the rotary disc. Thus, the complicated manufacturing procedures naturally results in an increase in the manufacturing and labor cost.
In addition, unless a protective casing is employed for the switch assembly, each contact point between the movable contact element and the fixed contacts is bared to ambient conditions and is, therefore, susceptible to ambient dust which is likely to result in a failure to complete an electric circuit.
Moreover, by the reason as described above, the number of switching positions available in the prior art switch assembly is fixed and, therefore, a user of the switch assembly cannot readily modify it to correspond to a proposed design of a circuit arrangement.